Driveway sinking & cracking help needed, please?

Hello Everyone,

What will cause a drive way to sink and crack like the driveway in this picture?
When having it repaired what should be done to insure that it does not sink and crack again.
This driveway as can be seen in the pictures, is severely sloping away from the house and toward the neighboring house.
The concrete is even pulling away from the side of this house, near the house, where the black sealer has been applied.
This house and adjacent driveway are 58 years old.

I've been told the base could have collasped due to age or water. How can I determine the cause of this driveway collapse & base failure?

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Driveway sinking & cracking help needed, please?

Settlement failure of concrete is almost always caused by inadequately prepared base. Possibly the concrete was placed directly on soil without installation of a 6 inch thick crushed stone base. In order to properly support concrete, it is necessary to first remove incompetent soil, which includes organic soil, weak soil such as silt, debris, and any other unsuitable material. After removal of unsuitable soil, the naturally occurring soil you have gotten down to is generally proof rolled with a tamper, then approximately 6 inches of crushed stone is placed, then the concrete is placed above that. The crushed stone allows the water beneath the concrete to drain.

Exact details of construction vary with region, however since you did not indicate the location, I can't discuss variations in design based on your location. In order to repair the problem, you need to remove the concrete, then prepare the base correctly as in the first paragraph.

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Driveway sinking & cracking help needed, please?

Quote:

Originally Posted by Daniel Holzman

Exact details of construction vary with region, however since you did not indicate the location, I can't discuss variations in design based on your location. In order to repair the problem, you need to remove the concrete, then prepare the base correctly as in the first paragraph.

Thanks Dan,

The driveway is located in Allen Park, a Southeastern Michigan city.

I'm concerned that improper drainage on the lot may be a contributing factor. Is my concern valid?

Driveway sinking & cracking help needed, please?

I don't know what you mean by improper drainage, but in general you do not want water accumulating underneath your concrete driveway, so any drainage scheme that allows water to accumulate beneath your driveway is trouble. Since you are in Michigan, you have relatively deep frost, so you need to take extra precautions to prepare the base. Ideally you would have free draining material (gravel, crushed stone, coarse sand) between frost depth, which could be up to 4 feet, and the bottom of the slab. This may not be practical, but the deeper the free draining material, the less trouble you are going to have with frost heave.

Driveway sinking & cracking help needed, please?

Quote:

Originally Posted by Daniel Holzman

I don't know what you mean by improper drainage, but in general you do not want water accumulating underneath your concrete driveway, so any drainage scheme that allows water to accumulate beneath your driveway is trouble. Since you are in Michigan, you have relatively deep frost, so you need to take extra precautions to prepare the base. Ideally you would have free draining material (gravel, crushed stone, coarse sand) between frost depth, which could be up to 4 feet, and the bottom of the slab. This may not be practical, but the deeper the free draining material, the less trouble you are going to have with frost heave.

Improper drainage must be an incorrect term that picked up while talking about this driveway.

Were you able to look at my pictures? Does it appear, the damage is a result of frost heave?

I really appreciate your help Dan. I can be a more informed consumer when I'm trying to choose a concrete driveway installer.

Driveway sinking & cracking help needed, please?

I looked at the pictures. Certainly there is evidence of frost heave, which is often caused by the presence of silty soil underneath the slab. Silty soil is unsuitable as base for concrete, since it traps moisture that freezes and expands the soil, causing the slabs to rise unevenly and then break. There are other possible causes of broken slabs, but generally the problem can be traced to improper preparation of the base. As I mentioned, you need to completely remove the slabs, remove all unsuitable soil, and install a proper base. You can break up the concrete into small pieces and use them along with crushed stone, it works well. Or of course your contractor can do so. You are not really going to know what the problem was caused by until you remove the slab and see the condition of the soil beneath the slab, but I am pretty certain the subgrade was not properly prepared, and that is what you will find.